Dengue viruses, a member of Flaviviridae family are mosquito born and are the causative agents for dengue fever. Dengue infection becomes a serious health concern globally because of the high mortality rate and the unviability of any proper treatment. Virus attachment to the host cell and subsequent fusion process are mediated by the envelope glycoprotein (E protein). The fusion process is driven by low pH induced conformational change of envelope protein in the endosomal compartment of the host cell. Due to the high prevalence of dengue viral infections and having no specific treatment, the development of novel antiviral agents is essential. Antiviral substances obtained from natural products, including medicinal plants, are potentially good targets to study. Extracts from the Carica papaya leaves, are commonly prescribed for the dengue patients but there are no scientific evidences for its activity against dengue. Hence we tried to investigate the anti-viral activity of compounds present in the leaves of Carica papaya against envelope protein of dengue 2 virus (DENV-2). Molecular docking approach using Autodock 4.2 was used in this study and results reveled that six compounds showed high inhibitory activity against the E protein. Six compounds (Stigmast-5-en-3-ol, (3á,24S) (M-30); D:A-Friedooleanan-7-one, 3-hydroxy (M-28); 5-Heptadecene, 1-bromo (M- 26), 2-(4'-Chlorophenyl)naphtho[2,3-b]furan-4,9-dione (M-27); Neurosporaxanthin methyl ester (M-25); 3,6-bis(t- Butyl)fluorenone (M-20); 5,11,17,23-Tetrakis(1,1-dimethylethyl) pentacyclo [19.3.1.1(3,7).1 (9,132).1(15,19)] octacosa-1(25),3,5,7(28),9,11,1 3(27), 15,17,19(26),20,22-dodecaene-4,12,16-triol-24-one (M-22)) showed high inhibitory activity against the β-OG pocket (hydrophobic pocket between the domain I and II) of envelope protein. These findings concludes that this selected compounds could serve as antiviral drugs for dengue infections. Further in-vitro and in-vivo studies are necessary to confirm their efficacy and to evaluate their drug potency.
